This invention relates to organometallic compounds of metals of Groups VIIb, VIII, IX, and X including manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum and their uses in chemical vapor deposition (CVD) methods for depositing films of metal or metal derivatives on a substrate or forming a metal or metal derivative in powder form. More particularly the invention relates in preferred aspects to organometallic precursor compounds derived from metals of Groups VIIb, VIII, IX, and X especially suited for high purity deposition of the metal or a derivative such as, for example, a metal silicide, utilizing CVD techniques.
Metal silicides derived from metals of Groups VIIb, VIII, IX, and X are attractive compounds in the electronics field particularly regarding the manufacture of integrated circuits and micro-electronics. Interest in metal silicides is increasing as device scale-down progresses due to its good thermal and chemical stability, low resistivity, wide process window and its small lattice mismatch to the silicon crystal lattice, which allows the metal silicide to be grown epitaxially on silicon. Furthermore, the metal films derived from metals of Groups VIIb, VIII, IX, and X selectively deposited on silicon substrates can be made to form self-planarized epitaxial metal patterns whose surfaces are atomically flush with the surrounding silicon.
CVD is a particularly useful technique for deposition of metal and metal silicide films as compared to other methods of deposition such as plasma vapor deposition (PVD) methods like sputtering, e-beam evaporation, molecular beam epitaxy, and ion beam implantation. CVD can also be used to provide flexibility in the design of manufacturing electronic devices including the potential to reduce the number of processing phases required to provide a desired product.
To date, CVD of various metals has been hampered by the lack of suitable precursor compounds. For example, conventional cobalt organometallic CVD precursors, such as Co(C5H7O2)2, Co(C5H7O2)3, Co2(CO)8, Co(C5H5)2. Co(C5H5)(CO)2 and Co(CO)3(NO) have not demonstrated satisfactory properties for use in forming device-quality cobalt silicide films. Co(C5H7O2)2 and Co(C5H7O2)3 have low vapor pressures and therefore require high temperatures to produce a vapor flow sufficient to support CVD. Co2(CO)8 is significantly more volatile and can produce cobalt metal coatings without the addition of a reducing agent, but is too thermally unstable to be a practical CVD precursor, giving rise to competing side reactions and decomposition during storage, even under vacuum or an inert atmosphere. Co(C5H5)2 and Co(C5H5)(CO)2 may be used to deposit cobalt films, but such films can be subject to severe carbon and oxygen contamination problems, even when H2 is used as a reducing agent. Likewise, Co(CO)3(NO) can be subject to unacceptable contamination with carbon and oxygen in the resulting cobalt and cobalt silicide layers when deposition is conducted at less than 350° C. or with a hydrogen flow of less than 500 standard cubic centimeters (sccm). Organometallic precursors based on the other metals in Groups VIIb, VIII, IX, and X have demonstrated similar shortcomings.
Therefore there remains a need in the industry for precursor compounds derived from metals of Groups VIIb, VIII, IX, and X suitable for CVD that can produce high purity, device-quality films of metals and/or metal derivatives such as, for example, metal silicide films. The present invention provides organometallic compounds which are well suited for such uses.